Preheat your oven to 425ºF/220ºC.
In a large bowl, combine ground meat, panko bread crumbs, green onions, egg, toasted sesame oil, red pepper flakes, garlic powder, onion powder, kosher salt, and black pepper. Mix until just combined.
Use a cookie scoop to scoop the meat mixture into 1 heaping tablespoon balls. Arrange them in a single layer on a parchment paper-lined sheet pan. Bake for 13-15 minutes, until golden brown and the internal temperature reaches a minimum of 160ºF (165ºF if using ground chicken or turkey).
In a small bowl, whisk together sriracha hot sauce, brown sugar, soy sauce, rice vinegar, and mayo to create a smooth sauce.
Toss the cooked meatballs with a few tablespoons of the spicy sauce until fully coated. Garnish with sesame seeds and extra sliced green onions.
If serving the meatballs as an appetizer, serve the extra sauce on the side as a dipping sauce.
If serving the meatballs as an entree, serve them over cooked white rice with a side of roasted broccoli or sauteed green beans. Drizzle extra sauce over the meatballs, rice, and veg.